Scientists engineer new-generation biological spine implant

Aug 3 2011
Many people who experience low back pain have degenerative disc disease. Traditionally, surgical treatment for this condition has involved removing the disc that was causing pain and fusing two vertebrae.

However, the fusion procedure often results in decreased mobility of the spine, and some patients still complain about pain after their surgery. As a result, researchers have been improving surgical treatment methods, inventing minimally invasive procedures and ever more advanced artificial discs.

The most recent development on that front has come from researchers at Cornell University and Weill Cornell Medical College in New York. They announced the creation of a biological spinal disc whose properties are similar to a natural intervertebral disc, and that they have successfully tested it in animal models.

According to the research team, the discs are engineered from collagen that wraps around the outside, and a hydrogel called alginate that fills out the middle part of the disc. Also, since they added new cell tissues to the implants, the researchers noticed that the devices actually got better inside the body, meshing with the original tissue due to the growth of these cells. Normally, artificially implants degrade over time, and there is evidence that they may release harmful substances into the bloodstream, such as titanium, which can cause liver and kidney damage.

In fact, "bone or metal or plastic implants are complicated structures which come with a mechanical risk of the structures moving around, or debris from the metal or plastic particles accumulating in the body from wear and tear," says Roger Hartl, MD, associate professor of neurosurgery at Weill Cornell Medical College and chief of spinal surgery at NewYork-Presbyterian Hospital/Weill Cornell Medical Center.

He added that aside from the biological advantage of integrating with the natural tissues and bones, the implants would also allow for less invasive and safer surgery to insert them.

The research is published in the Proceedings of the National Academy of Sciences and follows work unveiled earlier this year in both the U.S. and Europe on the use of advanced materials in spine surgery.

For example, researchers from the University of California Davis announced that surgeons at 24 medical centers throughout the U.S. tested the effectiveness of a hydrogel sealant made out of polyethylene glycol (PEG). The substance was shown to improve the outcomes of spine surgery in that it helped doctors better close the tiny holes in the dura - a sheath inside the spinal column that encloses and protects the spinal cord - that can cause leaks of the spinal fluid. Such leaks are a common complication of spine surgery and may lead to pain and repeated surgical interventions.

Meanwhile, scientists at the University of Manchester in the UK successfully tested an elastic gel based on nanoscopic polymer particles to relieve chronic back pain symptoms.

Injected into the affected part of the spine, the gel was shown to have the ability to replace an intervertebral disc due to its flexibility that allows for natural movements of the spine.